Optical interference filters are often based upon coherent interference between light from a multiple of optical paths. Such filters are highly sensitive to changes in optical path length due to the short wavelengths corresponding to optical frequencies. That is, a small change in one of the optical paths of an optical interference filter gives rise to a large change in the phase of the signal exiting the path because the small change gives rise to a large phase difference, thereby significantly affecting the how the shifted signal interferes with a signal exiting a different path. When the paths of an optical filter are provided by multiple interfering waveguides, such as in an integrated optical filter, it is difficult to maintain filter stability in the presence of varying environmental conditions because the varying environmental conditions give rise to variations in the optical path lengths and thus give rise to significant variations in how the waveguide signals interfere. Further, the difficulty of maintaining stability in an optical filter system increases as the number of optical paths in the system increases.